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Plants native from Cerrado generally have peculiar characteristics that allow tolerating water and nutritional stress. Astronium fraxinifolium is a Anacardiaceae tree of from Brazilian Cerrado. The aim of this research was to characterize A. fraxinifolium leaves morphophysiologically, in order to recognize characteristics related to acclimatization of the species in different soil conditions. Two populations of A. fraxinifolium were sampled in different study areas, A1 (Degraded Soil) and A2 (“Undegraded Soil”). Nitrogen compounds, total carbohydrates, chlorophyll, nutritional content, stomatal density and gas exchanges were quantified, comparing the areas. A high number of stomata was observed on the abaxial surface of A. fraxinifolium leaves, with a higher density occurring in A1 individuals. The values of chlorophyll and boron content were significantly higher in A2 plants. It’s possible that the lowest concentration of boron in A1 plants is related to chlorophyll production. Regardinf the other analysis, there weren’t significant differences between the areas. The results show that this species undergoes changes in production of chlorophyll, but liquid photosynthesis isn’t impaired, considering the low chlorophyll content in A1 being compensated by the higher stomatal density. Thus, these changes may be the result of acclimating this species to different environmental conditions to which it’s exposed.

Fire is an important ecological factor that influences the composition of the Cerrado vegetation in Brazil. In environments where fire is recurrent, tree species with seedlings/saplings that accumulate underground reserves and/or present distinctive underground structures (tuberous roots and root crowns) are more likely to reach maturity. Astronium fraxinifolium Schott is a tree species native to the Cerrado. The tree has xeromorphic characteristics, which perhaps is an adaptation to dry and rocky environments. To evaluate whether these morphological characteristics allow the species to recover from fire, an experiment was conducted where we compared burnt and unburnt saplings of A. fraxinifolium. We verified the emergence of buds closer to the root crown and compared the storage dynamics of lipids, starch, phenolic compounds, and mucilage between the burnt and unburnt saplings. Buds were observed in some of the individuals within 7 days of burning. The burnt saplings showed a high survival rate of 77.8%. Two cotyledonary buds per plant originated from the base of the stem. The rapid recovery of the species could be attributed to the starch reserves in the stems and roots, which helped nourish the buds and the resprouted seedlings. The results of our study showed the resprouting ability of A. fraxinifolium as a survival mechanism in response to fire events.

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